As a usual sliding type tripod constant velocity joint, for instance, a sliding type tripod constant velocity joint is known that is disclosed in JP-A-2000-256694 (Patent Document 1). In the sliding type tripod constant velocity joint disclosed in Patent Document 1, a tripod shaft part has a cylindrical form, and an inner peripheral surface of a roller has a cylindrical form. In this case, the roller is constantly located coaxially with the tripod shaft part. Accordingly, when a joint angle is applied, a direction in which the roller is apt to roll on a raceway groove (a roller groove) does not correspond to a direction in which the raceway groove extends. Thus, a slide arises between the roller and the raceway groove. As result, an induced thrust force is generated in the axial direction of the joint. The induced thrust force causes the vibration of a vehicle body or noise to be generated.
Thus, in order to reduce the induced thrust force, for instance, a sliding type tripod constant velocity joint is known that is disclosed in JP-A-2006-162056 (Patent Document 2). In the sliding type tripod constant velocity joint disclosed in Patent Document 2, an outer peripheral surface of a tripod shaft part has a spherical protruding form and an inner peripheral surface of an inner roller forming a roller unit abutting thereon has a cylindrical form. Thus, since the tripod shaft part can swing relative to the roller unit so that a direction in which an outer roller forming the roller unit is liable to roll on a raceway groove may be made to constantly correspond to a direction in which the raceway groove extends, a slide can be avoided from arising between the outer roller and the raceway groove. As a result, an induced thrust force can be reduced.
Further, as other structures, structures are known that are disclosed in JP-A-63-163031 (Patent Document 3) and JP-B-2763624 (Patent Document 4). A sliding type tripod constant velocity joint disclosed in Patent Document 3 includes a pair of intermediate members provided outside a tripod shaft part and a needle arranged between the intermediate members respectively and a side surface of a raceway groove. Further, in a sliding type tripod constant velocity joint disclosed in Patent Document 4, a tubular and integral intermediate member is provided in an outer periphery of a tripod shaft part, a needle can be circulated on an outer peripheral surface of the integral intermediate member and the needle rolls along the intermediate member and the side surface of a raceway groove.
Further, as other structure, a structure is known that is disclosed in JP-A-2003-65350 (Patent Document 5). In a sliding type tripod constant velocity joint disclosed in Patent Document 5, a rolling element is a spherical element. The rolling elements are mutually positioned relative to an intermediate member and supported by a cage. When a power is transmitted in this structure, between the rolling element and the intermediate member, and between the rolling element and a raceway groove, a large resistance is generated due to a slide as well as a rolling resistance.
Thus, in order to reduce the resistance, for instance, structures are known that are disclosed in JP-B-2763624 (Patent Document 4) and JP-B-3361096 (Patent Document 6). In sliding type tripod constant velocity joints disclosed in Patent Documents 4 and 6, a rolling element is a needle and supported by a cage so as to circulate on an outer periphery of an intermediate member. Thus, a resistance between the rolling element and the intermediate member, and between the rolling element and a raceway groove due to a slide can be greatly reduced.